Japan is becoming an aging society with the highest average life expectancy in the world. People are beginning to place more emphasis on living better, i.e., “the quality of life (QOL)”, rather than merely prolonging life. Under such circumstances, medical techniques are rapidly progressing, and techniques for reconstruction of organs damaged by trauma or disease are also advancing remarkably. Therefore, in recent years, a lot of attention has been focused on regenerative medical techniques in which organ tissue is reconstructed in the cell culture system employing cultured cells, and then transplanted to the target site.
To carry out such treatments, it is necessary to use tissue adhesive agents for tissue adhesion. The tissue adhesive agents currently used in the clinical field have been broadly classified into cyanoacrylate adhesive agents, gelatin-aldehyde adhesive agents, and fibrin glue adhesive agents. Cyanoacrylate adhesive agents employ adhesiveness by a polymerization reaction of the agents' cyanoacrylate monomers, and are superior in adhesive intensity and bonding speed. However, cyanoacrylate adhesive agents are synthetic agents which are not originally endogenous, and prevent healing by producing formaldehyde by hydrolyzation of a cured monomer, which causes toxicity to living organisms. Therefore, the problems exist that the site to be applied was limited, and the adhesive agents should not be applied to a site near a central nerve or blood vessel. Gelatin-aldehyde adhesive agents employ adhesiveness by a cross-linking reaction between a gelatin (biopolymer of the degenerated collagen) and formaldehyde or glutaraldehyde. However, the gelatin-aldehyde adhesive agents are also synthetic agents that are not endogenous. Although the gelatin-aldehyde adhesive agents also have sufficiently high adhesive intensity, since toxic aldehyde compounds are employed as a cross-linking agent, they are also biologically toxic. On the other hand, fibrin glue adhesive agents are made from a tissue-derived material, which employs adhesiveness by a reaction of blood coagulation. Although this type of adhesive agent is less toxic than the above described synthetic adhesive agents, the adhesiveness is low, and large amounts of fibrin glue should be used, since the fibrin glue itself is metabolized in vivo. Further, recently, some problems are being indicated relating to the topical inflammation at the site where the adhesive agent has been applied, since the fibrin glue is prepared and purified heterogeneously or the mechanisms of the adhesiveness of the fibrin glue are the same as the blood coagulation reaction.
Technology that provides a cell sheet having sufficient basal membrane-like proteins has been proposed. Conventionally, cell culture is conducted on a glass surface, or on the surface of a synthetic polymer compound along with a variety of surface processing. In order to achieve this, for example, various types of vessels made of polystyrene subjected to surface processing such as silicone coating, gamma irradiation, etc., are commonly used as vessels for cell culture. Cells that have been cultured and grown with these types of cell culture vessels, are detached and harvested from the surface of the vessel by a chemical agent treatment or a proteinase treatment such as trypsin. However, in cases where the cells are harvested by the above-mentioned chemical agent treatment, some disadvantages have been pointed out: the treatment method is cumbersome and complicated; the potential for contamination by impurities is increasing; and examples of defects, in which cells are caused to degenerate or are damaged by the chemical treatment, and lose their original function.
Thus far, in order to overcome the above-mentioned disadvantages, a number of techniques have been proposed by the present inventors. Especially, in Japanese Patent Application No. 2001-226141, a method for producing a cultured cell sheet which comprises steps of coating the surface of the cell culture support with a temperature responsive polymer having a lower or upper critical solution temperature ranging from 0° C. to 80° C. in water, having the cultured cell layers multi-layered by way of a conventional method, as necessary, and detaching the cultured cell sheet only by changing the temperature of the culture support. As a result of application of this method, a cultured cell sheet having sufficient strength can be produced. Furthermore, a thus obtained cultured cell sheet also retains basal membrane-like proteins, and also has improved adhesiveness to tissue, when compared with a cell sheet harvested using the above described dispase treatment. Moreover, PCT International Publication No. WO 02/08387 discloses a method for producing a cultured myocardial cell sheet, which comprises steps of culturing the cells of myocardial tissue on a cell culture support having a support surface coated or covered with a temperature responsive polymer, preparing a myocardium-like cell sheet, and subsequently, adjusting a temperature of the culture medium to a temperature greater than the upper critical solution temperature or less than the lower critical solution temperature, bringing the layered cultured cell sheet into close contact with a polymer membrane, detaching the cultured intact cell sheet together with the polymer membrane, and three-dimensionally structuring by a predetermined method. As a result of application of this method, a myocardium-like cell sheet and a three-dimensional structure were discovered to be constructed in vitro with reduced structural defects and with some of the functions of myocardial tissue. Neither of Application No. JP 2001-226141 nor WO 02/08387 have investigated conferring the flexibility to the cell sheet, and have discussed the use as tissue repair material for suppressing the air leakage, blood leakage or bodily fluid leakage from the surface of an organ. However, the use of such a cultured cell sheet as a tissue adhesive can be employed for the patient receiving tissue repair with an extremely high degree of safety, because the cell sheet can be prepared from the cell of the patient himself and, therefore, is highly safe.